多尺度残余应力定量分析及其对WC-Co系涂层摩擦磨损行为影响机制研究

Due to the existence of complex residual stresses, the high-velocity oxygen fuel sprayed WC-Co coating, as the protection surface of key components of aircraft landing gear strut, tends to suffer early damage or failure during the friction process, which would seriously affect the safety and reliability of the aircraft operation. To ensure the safety and quality of the coating, in present work, the advanced neutron diffraction and X-ray diffraction methods will be used. The nature, magnitude and distribution of residual stresses in multi-scale and different areas will be non-destructively determined. Based on the testing and theoretical models, the influence of residual stress on the fracture mechanics performance will be quantified. The evolution of residual stresses during friction process will be investigated, and its dominant impact mechanism will be discussed. Combined with the damage evolution, the failure and damage mechanisms under friction will be revealed by residual stresses. The implementation of the project will achieve the non-destructive quantitative analysis of residual stresses, and will enrich the worn mechanisms of thermal spraying coating based on the residual stresses. It will benefit the development and application of thermal spraying WC-Co coating, and to provide the related theoretical and technical supports for the independent development of large aircraft in China. The scientific and practical significance are remarkable.

由于复杂残余应力的存在，飞机起落架支柱等关键部件表面防护用超音速火焰喷涂WC-Co系涂层在摩擦服役过程中易发生突发或早期破坏失效，严重影响飞机运行的安全可靠性。为保障涂层服役安全和质量控制，本项目拟借助先进中子衍射和X射线衍射方法，无损可靠测定超音速火焰喷涂WC-Co系涂层的多区域（表面、内部）多尺度（涂层-基体间、相间、晶间）残余应力的性质、大小和分布；基于试验和理论模型，量化多尺度残余应力对断裂力学性能的影响；探究摩擦条件下的残余应力演变规律及主要影响机制；结合涂层摩擦损伤演变，揭示基于残余应力作用的摩擦损伤破坏机制。项目的实施将实现残余应力的无损定量分析，丰富基于定量残余应力的热喷涂涂层材料摩擦损伤失效机制，指导热喷涂WC-Co系耐磨涂层的研发和应用，为我国大飞机的自主研制及服役提供相关理论和技术支持，具有重要的科学意义和现实意义。

由于复杂残余应力的存在，表面防护用超音速火焰喷涂WC-Co系涂层在摩擦服役过程中易发生早期破坏失效，严重影响服役安全。为保障涂层服役安全和质量控制，本项目借助先进中子衍射和X射线衍射多种技术，可靠测定了超音速火焰喷涂WC-10Co-4Cr涂层/钢基体的多尺度残余应力（基体-涂层，相-相间），获得了涂层表面、内部及钢基体内部的残余应力分布状况，并结合涂层制备过程和特点，探讨了残余应力的形成机制。采用磨粒磨损和制动摩擦磨损试验，研究了不同摩擦形式和摩擦条件下涂层的摩擦损伤和残余应力行为，结果表明，随着摩擦形式和摩擦条件的变化，摩擦损伤和残余应力均发生明显变化；涂层近表层的残余应力变化显著，应力梯度明显。根据压痕法和裂纹扩展行为，结合断裂力学模型，研究了残余应力对涂层内部断裂韧性的影响，从而进一步揭示了与残余应力相关的摩擦损伤破坏机制。项目的实施初步建立了残余应力与涂层摩擦学行为之间的联系，丰富了热喷涂涂层材料摩擦损伤失效机制，为热喷涂WC-Co系耐磨涂层的研发和应用提供了相关理论和技术支持，具有重要的科学和现实意义。